Field of the Invention
The present invention relates to an optical device.
A Vertical Cavity Surface Emitting Lasers (VCSEL) is a semiconductor microlaser diode that emits light in a cylindrical beam vertically from the surface of a fabricated wafer. VCSELs offer significant advantages when compared to the edge-emitting lasers still used in the majority of fiber optic communications devices. To this end, VCSELs are packaged in TO (Transistor Outline) metal housings and mounted in receptacles for coupling with optical fibers.
In WO 9931737, which is hereby incorporated by reference, there is described a method for producing a surface-mounted optoelectronic component. The component provides good optical characteristics while being inexpensive.
It would be desirable to provide an inexpensive way of coupling VCSELs to optical fibers. The present invention aims to address this desire.
According to one aspect of the invention there is provided an optical device comprising: a surface-mountable optical component comprising a base member having a recess filled with a transparent filler, and an VCSEL element arranged in the recess; and a receptacle attached to the surface-mountable optical component, for receiving an optical fiber, thereby to optically connect the VCSEL element with the optical fiber. Accordingly, there is provided an inexpensive way of coupling a VCSEL element with an optical fiber. In particular, the surface-mountable component is suitable for a high volume production so that the overall costs of the optical device are reduced, even if the receptacle is produced in lower numbers due to varying requirements in the way the VCSEL is to be coupled to an optical fiber.
Preferably, the surface-mountable optical component further comprises one or more optoelectronic monitor elements arranged in the recess of the base member, for monitoring a predetermined emission parameter of the light emitter. The predetermined emission parameter may be, for example, the light emission power. Thus, the perfomance of the VCSEL can be monitored and any necessary corrections made.
In one embodiment of the invention, the optical device further comprises a reflector arranged between the light emitter and a light receiving end of the receptacle, for reflecting a part of the light emitted by the VCSEL onto at least one of the one or more optoelectronic monitor elements. This facilitates the arrangement of the monitor elements.
Preferably, the light emitter and the one ore more optoelectronic elements are mounted to a bottom surface of the recess adjacent to one another, and the reflecting surface of the reflector is at an angle relative to the bottom surface of the recess thereby to reflect light emitted from the light emitter onto at least one of the one or more optoelectonic monitor elements. This further simplifies the design of the optical device.
In one embodiment of the invention, the surface of the reflector facing the light receiving end of the receptacle is convex. Thereby, light emitted from the VCSEL is focussed onto the light-receiving end surface of an optical fiber received in the receptacle.
Preferably, the receptacle comprises an optical coupling element inbetween the optical fiber and the optoelectronic element, for focussing light from the VCSEL element onto the light receiving end surface of an optical fiber received in the receptacle. Thereby, the optical characteristics of the coupling of the VCSEL and the optical fiber are further improved.
The optical coupling element comprise a lens. The receptacle may comprise a recess for holding the lens. The lens may be spherical. This provides for a simple design while achieving a reliable optical coupling.
Preferably, the optical coupling element is in contact with the filler. This provides for an exact alignment of the VCSEL and the optical coupling element.
In one embodiment of the invention, the light receiving end portion of the receptacle is transparent to optically connect the VCSEL element with the optical fiber, wherein part of the surface of the transparent end portion facing the VCSEL, and/or part of the surface of the transparent end portion facing the light receiving end surface of an optical fiber received in the receptacle, is convex, thereby to form the optical coupling element.
In one embodiment of the invention, the receptacle comprises an optical coupling element inbetween the optical fiber and the VCSEL element, for focussing light emitted from the VCSEL element onto the light receiving end surface of an optical fiber, wherein the surface of the optical coupling element facing the VCSEL element is reflective to reflect part of the light emitted from the VCSEL element on at least one of the one or more optoelectronic monitor elements. Thus, no separate reflector is required while still allowing a simple arrangement of the monitor elements.
The optical device may further comprise an attachment element through which the surface-mountable optical component is attached to the receptacle, the attachment element comprising a through hole, wherein the surface-mountable optical component is arranged at one end of the through hole, and the receptacle is arranged at the other end of the through hole, whereby the VCSEL element is optically connected to an optical fiber received in the receptacle. By means of an attachment element, the design of the end portion of the receptacle for attachment with the surface-mountable optical element, and vice versa, is less restricted. Thus, pre-manufactured surface-mountable optical elements and receptacles can be attached to one another without requiring an adaptation of their design.
Preferably, the receptacle and the surface-mountable optical component are glued to opposing surfaces of the attachment element, respectively. This further reduces manufacturing costs.
In one embodiment, the optical device further comprises a reflector arranged between the VCSEL element and a light receiving end of the receptacle, for reflecting a part of the light emitted by the VCSEL element onto at least one of the one or more optoelectronic monitor elements; and an attachment element through which the surface-mountable optical component is attached to the receptacle, the attachment element comprising a through-hole, wherein the surface-mountable optical compenent is arranged at one end of the through hole, and the receptacle is arranged at the other end of the through hole, whereby the optoelectronic element is optically connected to the optical fiber, and wherein the reflector is held in the through hole.
The receptacle may comprise plastic, metal and/or ceramic material. The optical coupling element may comprise transparent plastic and/or glas material.
The filler may comprise a hardenable sealing compound. In particular, the filler may comprise epoxy resin.
According to another aspect of the invention, there is provided a surface-mountable optical component comprising a base member having a recess filled with a transparent filler, and a VCSEL arranged in the recess. Accordingly, a simple and inexpensive surface-mountable VCSEL component is provided which is suitable for high volume production.